C# align bitmap image

Hi. I would like to do some image processing in C# and need to align two images before applying a filter to them. I will attempt to do this by scanning the images at a fixed point in a small rectangular section, which I believe makes it necessary to use the Bitmap class. This section has a large amount of white pixels so I would like to take an average pixel value in this area to find the shift in the y-axis, as there is a large white horizontal bar going across the images. The x-axis will be the same in both images. I would like to setup a few test images with different shift values, from small to large, positive and negative, so I can search for the minimum value . This will require a scroll bar on the images to move them in small amounts. I am totally new to C#, and low level programmer. I have been trying to get the image in pictureBox1 with the following code.